The present invention relates to manhole closure assemblies and, more particularly, to manhole closure assemblies that can be maintained in a closed position.
Manholes are both well-known and widely utilized. Manholes are generally utilized as means for accessing an infrastructure, such as underground pipelines or cabling. Because manholes are essentially open holes into which an individual can fall, manhole covers are utilized to prevent entry into the manhole. A traditional manhole cover rests on a frame that is attached to the substructure above the infrastructure to be maintained. The cover rests on the frame and must be lifted and moved in order to gain access to the infrastructure beneath the manhole. Typically, manhole covers are formed of iron or other heavy metals and thus can weigh in excess of 100 pounds, creating a cover that is cumbersome to lift and otherwise maneuver. Although it can make manipulation of the cover difficult, the weight of the manhole cover is a benefit in that it helps to prevent the cover from being inadvertently removed from the frame, for example, by the force of passing vehicle traffic. It also helps to deter removal of the cover by unauthorized individuals.
It is known to lock a manhole cover to a surrounding frame. In many applications, the lock is, as far as is possible, tamperproof. The frequency with which the lock is used, i.e. locked and unlocked, may be high or low, depending on the circumstances. In many instances though a manhole cover will remain locked for a considerable period. The environmental conditions to which a manhole cover is exposed may also be severe and the cover may be subjected to a wide temperature range, the full effects of the weather e.g. rain and snow, traffic and the like. In an effort to effectuate a locking mechanism various padlock configurations, keyed locks or other similar locking devices have been utilized. The use of such locks has not gained popularity because they are cumbersome and difficult to utilize. They may also fail over long periods of exposure to environmental conditions.